Refactor API structure and add comprehensive user management features

- Restructure API v1 with improved serializers organization
- Add user deletion requests and moderation queue system
- Implement bulk moderation operations and permissions
- Add user profile enhancements with display names and avatars
- Expand ride and park API endpoints with better filtering
- Add manufacturer API with detailed ride relationships
- Improve authentication flows and error handling
- Update frontend documentation and API specifications

backend/apps/accounts/tests/test_user_deletion.py

@@ -0,0 +1,155 @@
+"""
+Tests for user deletion while preserving submissions.
+"""
+
+from django.test import TestCase
+from django.db import transaction
+from apps.accounts.services import UserDeletionService
+from apps.accounts.models import User, UserProfile
+
+
+class UserDeletionServiceTest(TestCase):
+    """Test cases for UserDeletionService."""
+
+    def setUp(self):
+        """Set up test data."""
+        # Create test users
+        self.user = User.objects.create_user(
+            username="testuser", email="test@example.com", password="testpass123"
+        )
+
+        self.admin_user = User.objects.create_user(
+            username="admin",
+            email="admin@example.com",
+            password="adminpass123",
+            is_superuser=True,
+        )
+
+        # Create user profiles
+        UserProfile.objects.create(
+            user=self.user, display_name="Test User", bio="Test bio"
+        )
+
+        UserProfile.objects.create(
+            user=self.admin_user, display_name="Admin User", bio="Admin bio"
+        )
+
+    def test_get_or_create_deleted_user(self):
+        """Test that deleted user placeholder is created correctly."""
+        deleted_user = UserDeletionService.get_or_create_deleted_user()
+
+        self.assertEqual(deleted_user.username, "deleted_user")
+        self.assertEqual(deleted_user.email, "deleted@thrillwiki.com")
+        self.assertFalse(deleted_user.is_active)
+        self.assertTrue(deleted_user.is_banned)
+        self.assertEqual(deleted_user.role, User.Roles.USER)
+
+        # Check profile was created
+        self.assertTrue(hasattr(deleted_user, "profile"))
+        self.assertEqual(deleted_user.profile.display_name, "Deleted User")
+
+    def test_get_or_create_deleted_user_idempotent(self):
+        """Test that calling get_or_create_deleted_user multiple times returns same user."""
+        deleted_user1 = UserDeletionService.get_or_create_deleted_user()
+        deleted_user2 = UserDeletionService.get_or_create_deleted_user()
+
+        self.assertEqual(deleted_user1.id, deleted_user2.id)
+        self.assertEqual(User.objects.filter(username="deleted_user").count(), 1)
+
+    def test_can_delete_user_normal_user(self):
+        """Test that normal users can be deleted."""
+        can_delete, reason = UserDeletionService.can_delete_user(self.user)
+
+        self.assertTrue(can_delete)
+        self.assertIsNone(reason)
+
+    def test_can_delete_user_superuser(self):
+        """Test that superusers cannot be deleted."""
+        can_delete, reason = UserDeletionService.can_delete_user(self.admin_user)
+
+        self.assertFalse(can_delete)
+        self.assertEqual(reason, "Cannot delete superuser accounts")
+
+    def test_can_delete_user_deleted_user_placeholder(self):
+        """Test that deleted user placeholder cannot be deleted."""
+        deleted_user = UserDeletionService.get_or_create_deleted_user()
+        can_delete, reason = UserDeletionService.can_delete_user(deleted_user)
+
+        self.assertFalse(can_delete)
+        self.assertEqual(reason, "Cannot delete the system deleted user placeholder")
+
+    def test_delete_user_preserve_submissions_no_submissions(self):
+        """Test deleting user with no submissions."""
+        user_id = self.user.user_id
+        username = self.user.username
+
+        result = UserDeletionService.delete_user_preserve_submissions(self.user)
+
+        # Check user was deleted
+        self.assertFalse(User.objects.filter(user_id=user_id).exists())
+
+        # Check result structure
+        self.assertIn("deleted_user", result)
+        self.assertIn("preserved_submissions", result)
+        self.assertIn("transferred_to", result)
+
+        self.assertEqual(result["deleted_user"]["username"], username)
+        self.assertEqual(result["deleted_user"]["user_id"], user_id)
+
+        # All submission counts should be 0
+        for count in result["preserved_submissions"].values():
+            self.assertEqual(count, 0)
+
+    def test_delete_user_cannot_delete_deleted_user_placeholder(self):
+        """Test that attempting to delete the deleted user placeholder raises error."""
+        deleted_user = UserDeletionService.get_or_create_deleted_user()
+
+        with self.assertRaises(ValueError) as context:
+            UserDeletionService.delete_user_preserve_submissions(deleted_user)
+
+        self.assertIn(
+            "Cannot delete the system deleted user placeholder", str(context.exception)
+        )
+
+    def test_delete_user_with_submissions_transfers_correctly(self):
+        """Test that user submissions are transferred to deleted user placeholder."""
+        # This test would require creating park/ride data which is complex
+        # For now, we'll test the basic functionality
+
+        # Create deleted user first to ensure it exists
+        deleted_user = UserDeletionService.get_or_create_deleted_user()
+
+        # Delete the test user
+        result = UserDeletionService.delete_user_preserve_submissions(self.user)
+
+        # Verify the deleted user placeholder still exists
+        self.assertTrue(User.objects.filter(username="deleted_user").exists())
+
+        # Verify result structure
+        self.assertIn("deleted_user", result)
+        self.assertIn("preserved_submissions", result)
+        self.assertIn("transferred_to", result)
+
+        self.assertEqual(result["transferred_to"]["username"], "deleted_user")
+
+    def test_delete_user_atomic_transaction(self):
+        """Test that user deletion is atomic."""
+        # This test ensures that if something goes wrong during deletion,
+        # the transaction is rolled back
+
+        original_user_count = User.objects.count()
+
+        # Mock a failure during the deletion process
+        with self.assertRaises(Exception):
+            with transaction.atomic():
+                # Start the deletion process
+                deleted_user = UserDeletionService.get_or_create_deleted_user()
+
+                # Simulate an error
+                raise Exception("Simulated error during deletion")
+
+        # Verify user count hasn't changed
+        self.assertEqual(User.objects.count(), original_user_count)
+
+        # Verify our test user still exists
+        self.assertTrue(User.objects.filter(user_id=self.user.user_id).exists())